Two-stage filter



w. LEWIS, JR.. ETAL Sept. 30, 1952 TWO-STAGE FILTER Filed Feb. 12, 1951INVENTOR. WLeMS,J/1 4.7.' C//ffon FIG. 2

A TTOR/VE Y Patented Sept. 30, 1952 UNITED ,STATES PATENT oFFlcE- jTWO`STAGE`FIETER l Wat-ner1Lewis,-.Jr.,and Lloyd T'. CliftongfTI-iulsafxkla., assigner-s toV War-ner Lewis Compatri. ',liulfsa,V Okla., lacorporation of..ll)'elaware. ApplicationrFebruarylZ, 1951-,:S'e'rial No;21m-'525 3 claim, (o1. .21o- 1311)-l This invention relates totimprovements' in filtering. devices, .and more: particularly, but. .notbyv way .of limita-tion, to .anixnproved filter' employing.. twofiltering' steps or operations;

The usual filter utilizedV tot filter: light.v hydrocarbons; suchasfhigh octane-gasoline or: ietf-nels. normally employsy ,only ay.surface type'. filtering medium;` Therefore, Aparticularly"when thefilter.'-4 ing device: isf utilized .on the: fuel. lines of aircraft.i-ce.; crystals and large.; contaminants .soon cake on the outer.surface of the filtering medium to` precludey Va substantial: flow? ofuidzthrough the' filter-ing medium and. rendering; the entire filteringdevicauseless. f

The-'present' inventionrelatesto af filtering de-v vice.- particularly`adapted. forr-ltering: light hydrocarbons and employing'. two.filtering. operations. The. hydrocarbonA stream is. rst passed inwardlythrough a'volumetypelterin'g medium where-icev crystals` and; largecontaminants are removed from thev stream. i The stream is then passedthrough a surface type filtering; medium before; being discharged. fromthe: filtering deviceto remove,- the finerF contaminants; Avolumextype'. ltering medium, asV it' is well known. will absorb or remove. a.large quantity of: contaminants before passage-of fluid therethroughmaterially restricted. Therefore,xthe present iiltering device will havea: substantially"longerl `service.- life. than conventional?, filtering:devicesl and theV eicient-.operation of the surfacetype filtering mediumwill not be` impaired byvaldeposition of large-contaminants thereon.

important object of. this invention: isi t provide a two stage.filtering device:

Another objects: this invention-is to provide'v a filtering devicewhich' maybe easily and enrciently broken;y down for'rlspectipnor'repair-.withe 01115 being disconnected from a fluid flow line:

A further' object 0f. this. invention isjfto provide a .filtering device1 wherebythe; filtering? rne-v diums thereof may be easilyfreplaced A.still` further: object` of. this: inventiony is t0 provide an..emcientillltering.. devlcehaving alongservice-life.

,Another obieoi Off this* invention -is-to provide @novel i'ilteringdevice which..may be..ecolrlomically manufactured..

v'Qtherobjectsv and advantagesofthe invention will be.Y evident from thefollowingY detailed, description, readin.v conjunction with the, accom;panyingf. drawingst which illustrate` our, invention.-

In the drawings:

Figure.111sdelen-vieweranovetnltennszdef v1.96 l

Figure-21ste. -sectionalzviewtakenxon lines:2`'--2 eilig". 1;

Figure 3'is a perspectlveaviewvof theouterre.- pack-element.

Figuren is an elevational viewzofrthellter with portions broken'awayfr'claritm Referring'to the drawings: ini detail, reference character 2generallyindicates aznovelltering device :comprising a' relief. valve 4having' 'an inlet passageway 6 and outletii passageway thereithrough;The passageway/s E'Iand 8 are suitably interconnected bypassagewaysinot' shown) hav-- ing: springf'loaded pistonsy (not shown)Vtherein to' providera bypass .of fluid. directlyfroni: the inlet@ totheoutlet 8' instheusua'l manner when ow of fluidthroughithe"filter'2-isbbstructedl Furthermore, ,thev passageways B" and. 8' 'are iiiter"nally threaded (not. shown). orfotherwiseiadapted for interconnectionwitha'fluid flow line (not shown). l

The relief valve y4 isy secured to.' the upperfa'c'e I (Fig. 2)' 'of acircularshaped headplatef 12.1 Aperturesl I4 and I6 areproviciedvthrough' the platelZ in aligned'. relation. with the passage-- Ways 6and 8 respectively.` They upper.v endy f8 of a center `tubezzll issecured. inthe' aperture I6." The tubev20 extends downwardlyfromtheplate l2 and is provided with a' pluralityfof slots2`2' in the' wallsthereof for purposes aswill be;here'-`t nafterset forth. Av plug 24issecu'redrin the lower venel 26 of theLtubeZ toprecludeow'f ofi fluiddownwardly outiof the-'tubelif Aro'df-BU issecured to theiplug' 24land'extendsrdownwardly' therefrom.

AA tubular shaped filter' element 32 lsf'telscoped' over 'the tube 20and extendsov'er substantially' thetentire 'length' thereof to' coverthe 'slo'tf'rT 2'2'." The filter element' 32 is` afsurfa'ce type filter;being composed of resin impregnated paperorthe like: An aperturedcircular shaped element 34, preferably formed out of cork Aor the like,is'disposedl on the upper end of the filter 32 and cooperateswithazsharpenedv circumferential'ange 3B pro"- vided on the lower' face'3'8' `of' the head'plate" to preclude flow of fluid 'downthe-wa1lsf=oftiietube 20 and hence bypassing the filter 32. An aperturedcircular plate 40 is also provided on thelower. end of the .filter 32.VThe -platell engages` an upwardly` extending and sharpened`circumferential flangel 42 providedon an' apen-f turedretaining plate44.- The :retaining-plate 441 is telescopically disposed on thetubef20-fandis'@ in .turn sealed ytothe tubev 20- by a-sealing1 ring;(not shown) to4 preclude.. iluidf` byIJaSSinga the` filter'l 32byiiowing upwardly. along-...the wallsaoi'i` An outer tubular iilterunit or repack generallyr designated at 58 (see also Fig. 3) istelescopically disposed over the filter element 32. The repack 58comprises an inner tube 80 and an outer tube 62 interconnected by upperand lower caps 64 and 66 respectively. The inner tube 60 extendsslightly higher than the outer tube 62 and has its upper end sealed in acircumferential groove 68 provided in the lower face 38 of the headplatey l2. The lower end of the inner tube 50 is sealed in acircumferential groove provided in the lower retaining plate 54. Theplate 54 retains the repack unit 58 in assembled relation over thefilter 32. A plurality of apertures 'I2 are provided in the tubes 60 and62 and the lower cap 66 to permit flow of fluid throughthe unit as willbe more fully hereinafter set forth. A volume type filtering material14, such as a producttermed Caslen, is packed in the lter unit 58between the tubes 60 and 62 to iilter iiuid passing therethrough.` Asclearly shown in Fig. 3, the outerftube 62 isl bent inwardly at 'l5 and16, and the caps 64 and,66 arey out away at 18 and 80 respectively toyprovide a vertical passageway 82. Referring again to Fig. 2, it will-benoted that the passagewayl 812v isdisposed in aligned relationship with4the inlet passageway 6 and aperture I4. A cylindrical housing 84 isdisposed over the repack 58 and has its upper end 86 sealed inanother'circumferential groove 88 provided in the lowerface 3B of thehead plate 2. The lower end 90 of the housing 84 is enclosed and isprovidedwith an apertured bushing 92 in the central portion thereof toreceive the downwardly extending rod30. A suitable sealing ring 94 iscarried in the bushing 92 around the rod 30 to preclude leakage of fluidthrough the bushing 92. An apertured nut 96 is threadedly secured in thebushing 92 around the rod 30 for purposes as will be hereinafterv setforth. vvA smaller apertured nut 98 is threadedly secured. in alongitudinal bore |00 provided in the lower end' of the rodv 30'. Thenut 98 is threadedly secured in the bore .|00 by means of left handthreads 99-forpurposes as will'behereinafter set forth. The `bore |00communicates at its upper end with a. transverse aperture |02 in turncommunieating with the interior of the housing 84 to provide aA drainpassageway for the housing. A suitable pet cock |04 is threadedlysecured in the nut 98in communication with the bore |00 to control"v thedraining of the filtering device 2 ina well known manner.

y Operation K In operation, the hydro-carbon stream, or-any other fluidto be'ltered, is pumped through a f'lid flow line -(not shown) into thepassageway 6.v The iiuid will then iiow downwardly through the aperture|4 andthe vertical passageway 82 asf-'shown by the arrowsv in Fig. 4.From Figs. 2"and 4 it -willbe noted thatan annular chamber? '|06' is-provldedbetween the vwalls of the ed. From the repack 58, the fluidflows into the annular chamber |08 between the inner tube 60 and theouter-,surface of the lterelement 32. It kwill be noted that the upperand lower ends of thetubel) are sealed off by the head plate l2 and theretaining plate 54 respectively,

' therefore the fluid is constrained to pass through the repack 58 inorder to enter the chamber |08,l and by-passing of the repack 58 isprohibitedl Furthermore, the upper and lower ends ofthe `filter element32 are sealed as previously set forth,'hence by-passing of the innerlter element. 32 is also precluded. 1

Theiilter element 32, as `previously set forth, is a surfacetypefiltering element, therefore the finer or 4smallercontaminantslcontained in the iiuida're deposited on the outer surfacethereof. These smaller contaminants, will, of course, eventually form acake or layer (not shown) on the outer surface'of theiilter 32 to reducethe flow -of fluid through the'iilter. However, since the largercontaminants have previously been ltered outby the"1ilterlng medium 14,a cake will not be formedv on thefllter 32' until after many hoursy of:operation.

After passing/through the filter element 32, the-fluid flows throughtheslots 22 into the center tube 2l) and hence :through the aperture I5and outlet'passageway Sto any desired destination- (not shown). Intheevent the repack 58 becomes 'substantially filled with largecontaminants, or a cake is formed -on the outer surface' of the filterelement 32, the differential pressure of the fluid between the inlet 6and out-1' le't `8 will be increased. Upon fan increase of' thisdifferential pressure above a predetermined amount, the passageways (notshown) interconnecting the inlet 6 and outlet 8 will be opened in' theusual manner'to permit' a bypassing of both the repack 58 and 1ilter'32.

To assemble the filtering device 2, the inner filter element 32 is flrstplaced over the slotted center tube 20 with.' the upper sealing plate 34thereof in engagement with the circumferential flange 36.' AThe outerfilter or repack 58 is then telescoped over the filter 32 with the upperend of the tube 'seated in the circumferential groove 68' andthelvertical groove- 82 in alignment with the apertureil4. The sealingplate 44 and spring 50 `are then placed overthe tube 20 with thecircumferential flange 42 in-englagementwiththe bottom seal 40 of theiilter 32. Next, the retaining plate 5.4 is placed over the rod 30 inengagement with theA lower end of the tube 60 andthe spring-50Aas`shown'in`1ig.2. The nut 56 is then threaded onto the rod 30 in con-ltact with the-retaining 'plate-"54., `Itwillthlen belrea'dilyfseenl thatthiiilter'3'2 land repack. `58 arefsecured inoperatin'gposition onY thehead-4 plate I2 t'hrough'thef-'mediumof the tubeV20Wandn rod 30 v n fThe shell or housing' 84 Amay then be freelytelescoped over the repack58 with the upper vend 86 thereof in the circumferential groove 80 ofthe head plate l2, and the bushing 92 over the lower end of the rod 30.The housing 84 is retained in sealing engagement with the head plate l2by the nuts 96 and 98 through the medium of the rod 30 and center tube20. The nut 96 is first secured tightly lin the bushing 92 and the nut98 is then threaded into the bore |00. The nut 9 6 is then backed ofi orturned in a counterclockwise direction into contact with the lower nut98. Since the rod 30 is rigidly secured to the head plate l2, and thenut 98 is secured by the left hand threads 99 in the rod 30. thecounter-clockwise movement of the nut 96 will not loosen the nut 98.Furthermore, the reaction force exerted by the nut 96 on the bushing 92will force the housing 84 against the head plate I2 to provide anefficient seal. Torsional forces exerted on the rod 30, and hence thecenter tube 20, will thereby be reduced to a minimum. The reduction oftorsional forces is an important factor when vthe filtering device 2 isconstructed out of light-weight materials, as when utilized to filterhigh octane gasoline or jet fuels in aircraft.

Lastly, in the assembling operation, the pet cock |04 is threadedlysecured in the lower nut 98 and placed in a closed position to precludeflow of fiuid out of the housing 84 through the aperture |02 and bore|00. To install the filtering device 2, it is simply necessary to threadthe i inlet and discharge fuel or fluid flow lines (not shown) in theapertures 6 and 8 respectively.

From the foregoing it is apparent that the present invention provides anovel filtering device employing two filtering steps. The stream to befiltered is first passed through a volume type filter to remove thelarger contaminants and ice crystals, and then the stream is passedthrough a surface type filter to remove the smaller contaminants. It isalso apparent that the filtering device may be easily and efficientlyassembled or disassembled for inspection or repair without disconnectingthe fluid flow lines. One or both of the filtering elements may bereplaced in a minimum of time. Furthermore, the present inlventionprovides a practical and efficient filtery ing device having a longservice life and which may be economically manufactured.

Changes may be made in the combination and arrangement of parts asheretofore set forth in the specification and shown in the drawings, itbeing understood that any modification in the precise embodiment of theinvention may be made within the scope of the following claims Withoutdeparting from the spirit of the invention.

'We claim:

1.` In a filtering device comprising a head plate, inlet and outletapertures in the head plate, a tube secured in the outlet aperture andextending downwardly therefrom, a plurality of slots voiumetype nner tothe tube, and a housing 7 secured to the head plate around the volumetype filter providing a passageway from the inlet aperture to the volumetype filter.

2. In a filtering device comprising a head plate,

V,inlet and outlet apertures in the head plate, a

slotted tube secured in the outlet aperture and extendingdownwardly'from the head plate, a plug in the lower end of the slottedtube, a rod secured to the plug and extending downwardly therefrom, asurface type filter element surrounding the slotted tube, means forvsealing the oppositeends of said filter element to the tube andsupporting said filter element on the tube, a tubular repack unittelescoped over the filter element, the inner bore of said repack beingsealed at its upper end to the head plate, a retaining plate carried onsaid rod for supporting the repack and sealing the lower end of therepack inner bore, a volume type filtering medium in the repack, ahousing telescoped over therepack, and means on said rod for retainingthe housing in sealing contact with the head plate, said housingproviding a passageway communicating with the inlet aperture and theouter surface of the repack.

3. In a filtering device comprising a head plate, inlet and outletapertures in the head plate, a slotted tube secured in the outletaperture and extending downwardly from the head plate, a plug in thelower end of the slotted tube, a rod secured to the plug and extendingdownwardly therefrom, a surface type filter element surrounding theslotted tube, means for sealing the opposite ends of said lter elementto the tube and supporting said filter element on the tube, a tubularrepack unit telescoped over the filter element, said repack comprising aperforated inner tube and outer tube, caps for securing the oppositeends of the outer tube to the inner tube, means for sealing the upperend of -the inner tube to the head plate, a retaining plate carried onsaid rod for supporting the repack and sealing the lower end of therepack inner tube, a volume type filtering medium in the repack, ahousing telescoped over the repack, and means on said rod for retainingthe housing in sealing contact with the head plate, said housingproviding a passageway communicating with the inlet aperture and theouter surface cf the repack.

WARNER LEWIS JR. LLOYD T. CLIFTON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 410,767 Pierce Sept. 10, 18891,563,904 Kerckhoif et al. Dec. 1, 1925 1,624,832 Glover Apr. 12, 19271,999,913 Merritt Apr. 30, 1935 2,431,782 Walton et al Dec. 2, 19472,550,853 Nugent May 1, 1951 FOREIGN PATENTS Number Country Date 8,374Great Britain Apr. 6, 1911

